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Genes and DNA

Genes and DNA. Chapter 6. DNA Fun Facts…. Nearly 6 feet of DNA strands are located in the nucleus of every cell in your body We have over 3 billion base pairs in our DNA Every person’s DNA is 99.99% similar to that of another person

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Genes and DNA

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  1. Genes and DNA Chapter 6

  2. DNA Fun Facts… • Nearly 6 feet of DNA strands are located in the nucleus of every cell in your body • We have over 3 billion base pairs in our DNA • Every person’s DNA is 99.99% similar to that of another person • It is estimated that 98.5% of the chimpanzee genome is the same as the human genome.

  3. Sec. 1: What does DNA look like? • Goals: • List 3 important events that led to understanding the structure of DNA • Describe the basic structure of DNA • Explain how DNA can be copied

  4. Important People in DNA’s discovery…. Amount of A=T, G=C • 1…Erwin Chargaff • 2…Rosalind Franklin • 3…James Watson and Francis Crick • Chargaff’s rules! • She discovered the shape of DNA using X-rays • Built the 1st model of DNA

  5. DNA • Short for “deoxyribonucleic acid” • Is a large chemical molecule that resembles a twisted ladder • Contains all the genes that determine the traits of an organism • Found inside every living cell on Earth

  6. DNA contains the following: • Four Bases (these make the ladder rungs) • A=adenine, T=thymine, G=guanine, C=cytosine • Sugar and Phosphate (make the sides) ( Sides are also called the backbone )

  7. Bases are complementary: • A always pairs with T • G always pairs with C • Therefore….CCTAG complementary to GGATC

  8. Nucleotides • They are the subunits of DNA • They contain a sugar, phosphate, and one of the 4 bases:

  9. Genome: • the genome is the entirety of an organism's hereditary information

  10. DNA’s Shape: • Double helix Tap for Brainpop !

  11. When copies are made… • DNA is copied every time a cell divides. • Each new cell gets a copy of all the DNA

  12. Making Copies of DNA: • Replicate: this means making copies • Each base only pairs with one other base: • A-T • C-G • This means each side of the DNA strand is complementary

  13. Write the complimentary strand: • ATCGTTAGGCT

  14. How copies are made: • During replication, the DNA molecule splits (unzips) down the middle where the bases meet • As the bases on the original molecule are exposed, complementary nucleotides are added to each side of the ladder “see diagram next slide”

  15. Tap for animation Each half of the molecule is old DNA, and half is new DNA:

  16. Where do the nucleotides come from?? Nucleotides come from a variety of sources, but primarily from the foods you eat. Animals and plants also have genomes, do not forget. So, when you eat vegetables or any kind of meat or fruit, you're also ingesting that organism's genome. So, your body metabolizes all these things, along with proteins, lipids, carbs, etc. So, the nucleic acids are metabolized and broken down into nucleotide bases. These can then be used to replicate your own genome. Additionally, some of your own cells that die will release their genomes, and the nucleotides in these can be recycled.

  17. Sec. 2: How DNA Works

  18. It is the SEQUENCE • of nucleotides that creates the code of life. • One half strand of DNA has a complementary half and the sequence is preserved.

  19. The bases in DNA: • The bases read like a book. • A, G, T, C form the alphabet of the code. • Groups of THREE bases code for a specific amino acid. • Strings of these amino acids make up proteins. • Each gene is a set of instructions for making a protein.

  20. The big idea: • Gene’s Sequences of A’s, G’s, T’s, and C’s tell the cell what Protein to make.

  21. Proteins: • Are everywhere in cells. • Act as chemical messengers. • Are the reason living things look so differently from each other.

  22. 1.Enzymes are proteins. Enzymes catalyze chemical reactions - helping reactions happen as needed. 2. Proteins are structural elements of organisms. 3.Proteins make up parts such as hair, horns, hooves, nails, ... 4. Proteins are integral parts of membranes, helping to transport materials and acting in cell recognition. 5. The cytoskeleton that gives cells shape and support are made of protein, as well as the spindle fibers, cilia, flagella, centrioles, ... 6. Proteins carry oxygen, give immunity, contract muscles, ..

  23. Genes Make Proteins (which are made up of amino acids): • 1. A copy of a portion of DNA is made and transferred out to the cytoplasm • This copy is called mRNA (messenger RNA) • 2. The copy is fed through a ribosome,three bases at a time • 3. Transfer molecules feed the correct amino acid to the ribosome • 4. Amino acids are dropped off and joined together to make the correct protein

  24. arginine - arg - R ( • asparagine asn - N (gif, interactive) • aspartic acid - asp - D (gif, interactive) • cysteine - cys - C (gif, interactive) • glutamine - gln - Q (gif, interactive) • glutamic acid - glu - E (gif, interactive) • alanine - ala - A (gif, interactive) • glycine - gly - G (gif, interactive) • histidine - his - H (gif, interactive) • isoleucine - ile - I (gif, interactive) • leucine - leu - L (gif, interactive) • lysine - lys - K (gif, interactive) • methionine - met - M (gif, interactive) • phenylalanine - phe - F (gif, interactive) • proline - pro - P (gif, interactive) • serine - ser - S (gif, interactive) • threonine - thr - T (gif, interactive) • tryptophan - trp - W (gif, interactive) • tyrosine - tyr - Y (gif, interactive) • valine - val 20 amino acids "building blocks" of proteins

  25. D N A

  26. Watch the “Gene Scene” !

  27. Genome: the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA.

  28. Human genome analogy: • An analogy to the human genome stored on DNA is that of instructions stored in a library: • The library would contain 46 books (chromosomes) • The books range in size from 400 to 3340 pages (genes) • which is 48 to 250 million letters (A,C,G,T) per book. • Hence the library contains over six billion letters total; • The library fits into a cell nucleus the size of a pinpoint; • A copy of the library (all 46 books) is contained in almost every cell of our body.

  29. DNA Song!http://www.youtube.com/watch?v=FUA6_Ucw3i4 Gene therapy and colorblindness video

  30. Changes in Genes: • When there is a change in the order of bases in an organism’s DNA it is called a Mutation

  31. Three Types of Changes in Genes:

  32. 1. Substitution: Base pair replaced • Ex.

  33. 2. Base pair added: Insertion: Ex.

  34. 3. Base pair removed: Deletion • Ex.

  35. Genetic disorder: Sickle Cell Anemia • Happens with red blood cells • GAA changed to GTA • This substitution makes red blood cells that have a distorted shape:

  36. Mutation can result in: • 1. A genetic disorder (possible death) • 2. An improvement • 3. No change at all

  37. Big Deal? • Cells do make special proteins to detect errors in DNA (DNA police!) • When an error is found, it is usuallyfixed • (but not always) Correct sequence stolen!

  38. Mutagens: • Things that can cause a mutation in DNA • Examples: • UV radiation, excess of X-Rays, asbestos( see next slide!), chemicals in cigarette smoke

  39. ASBESTOS: Wrapped around a pipe In the ground

  40. Why was it used? From the time that asbestos was discovered in the first century, its properties amazed people. It had the ability to protect from heat, flames, noise and condensation. In fact, early Greeks used it for both lamp wicks and clothing. By the 1800s, asbestos was considered to be even more of a “miracle mineral” and was used in conjunction with the growth in industry. Using this readily available and inexpensive material in all manners of household construction offered many benefits, with no visible drawbacks, at the time. Asbestos could be used to fill spaces, cover items, mix with liquids or combine with paints. It could keep flames lit, heat in, cold out, sound clear, damp areas dry and cement strong. In fact, by the 1970s it seemed that mankind was still discovering uses for asbestos. It was put into paints, adhesives, clay, crayons, protective wear, metal ware and, of course, appliances. With its adaptability, it seemed to meet countless needs in different ways.

  41. Genetic Engineering • Transfer genes from one organism to another: Human milk gene in cow Firefly gene in a plant

  42. Genetic Identification: DNA fingerprinting Identifies unique patterns in an individual’s DNA

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